Instrument for reproducing and magnifying sound-waves.



n c. H. HULBERT. INSTRUMENT FOR REPRODUCING AND MA-GNIFYING SOUNQWAVES.

' APPLICATION FILED- JAN. 15. 1914.

1,153,431.. Patented Sept. 14, 1915.

4 3 SHEETS-SHEET l. 4 10 C. H. HULBERT.

INSTRUMENT FOR REPRODUCING AND MAGNIFYING SOUND WAVES.

APPLICAHON HLEU JAN. 15. 1914.

1 5 153,431 Pai'cnredSqfi. 14, 1915.

l/vi/hmoozo CLINTON HORACE HULIBERT, F MANILA, PHILIPPINE ISLANDS.

-for producing, reproducing or magnifying speech or any other tone.

In the drawings :'Figure 1 is a vertical sectional View of the instrument on the line A A, Fig. 2; Fig. 2 is a top plan view of the instrument, the cover beingremoved; Fig.

3 is a perspective view of. the instrument; Fig. at is a detail sectional view showing the drums used in multiple; Fig. 5 is a plan view of another embodiment of my invention; Fig. 6 is a longitudinal sectional view of a telephone receiver embodying my invention; Fig. 7 is a similar view of a telephone receiver showing a still further embodiment of my invention.

The reference numeral 1 represents the main body of the case which is preferably made of bronze or other nonunagnetic metal having a cover 2 on which is secured the cap 3, there being a rubber gasket 1 between the cap and cover, said cap and cover being of bronze or other non-magnetic metal. The cover 2 is supported on a suitable insulation k which in turn is secured on a lug 5 within the casing. The casing is supported on feet 6 having soft rubber cushions 7. Soft rubber gaskets S are secured on the upper side of the feet to insulate the screws which pass theretln'ough, thereby materially lessening the liability of outside sounds passing into the casing. Peep holes 9 are constructed in two sides of the casing, said holes being covered with glass. A cap 3 similar to cap 3 is secured on the bottom of the casing over a rubber gasket 4. lhe cover 2 and thebottom of the casing is provided with an open ing having lugs 10 and 11 on opposite sides thereof, a pole 12 composed of laminated sheet iron being secured at its outer end between the lugs 10 by means of a bolt 13 which passes through slot 14: in said pole. Insulation 15 is interposed between the lugs 10 and the pole 12. The lower pole 16 is of the same construction as the pole 12 and is secured between the lugs 11 by means of the bolt 17.

Specification of Letters Patent.

Application filed ilanuary 15, 1914. Serial No. 812,298.

Patented se t. 1a, 1915.

18 are insulations. I Upper and lower bobbins 19 and 20 havmg respectively, suitable insulation 21 are wound to form magnets 22 and 23. Four permanent magnets 24, 25, 26 and 27 are disposed in the case at right angles to each other around the pole 16, the bobbins ex- Each permanent magnet is held in place by means of brass screws 28 which pass through the outside member of the bobbins 19 and 20 asshown in Fig. 1, thereby supporting the bobbins from the casing. The bobbins may be adjusted relatively by means of these icrews as will be readily understood from The suitably shaped cell 29 of the instrument is composed of two very thin metallic dia'phragms, forming opposite walls, capable of vibration, the fiat surfaces of which are brought close together but do not touch each other except at their perimeter wherethey are clamped together, or better still soldered together, except at two points where openings are left to permit of the pars sage of air gas or liquid waves. In the construction of the cell it is absolutely essential that the metal be smooth and true. For sensitive work very thin metal must be used, while for heavy and loud tones correspondingly heavier metal may be used. The most satisfactory results that I have obtained were from a cylindrical cell four inches in diameter, with diaphragms 1/150 inch in thickness, separated about 1/16 inch. On increasing the size of the cell, the metal must be thicker in proportion to the width. I have obtained the best results when the diaphragms of the cell are the same distance apart as the poles are adjusted 011 the outside. The strain is then evenly'divided and the thin diaphragms lie in aneutral point: therefore the strong magnets do not tend to cause the cell to bulge. The cell gives double tone waves as both diaphragms vibrate to and fro making a double compression and expansion, which action causes the air to rush in and out. If a combustible gas is passed through the cell to a lighted burner the flame clearly records variations in currents and tones. When the cell is filled with liquid and the openings restricted to that of a small glass tube, va'riation's in reduced currents in the instrument are visible.

When electric clirrents enter 1n one direction tending between the arms of the magnets."

touching it. are secured to the perimeter of the bobbins 19 and 2Oforl1olding and centering the cell '29 midway between the bobbins.

31 are fiber washers secured to the screws 30 which bear on the cell.

the tubes 34 and 3-5.

Twooutlets 32 are secured in the peripheral openings of the drum 29 to which are connected rubber tubes33, the other .end of said tubes being connected respectively to 36 and 37 are caps for said tubes secured to the casing by means of chains 38.' The caps are to be screwed on when the instrument is not in use. When only one side of the instrument 1s m use the other side should be capped.

- 39 and 10-represent four binding posts,

two for each coil or bobbin with conductors 41 and 42 so that each coil can be connected in series or in multiple.

When alternating currents are used, direct I current electromagnets should be substitued for the permanent magnets, as the alternating current will demagnetiz'e the permanent magnets. Multiple windings may be used in the type of instrument shown in Fig. 1 when it is desired for laboratory work. Clear records are obtained from the coarse wire side when thermo-couples, for example,

- copper and iron, of a. very weak voltage are 'used. When a circuit breaker is added either in series or in multiple with the junction to be tested,'and the couple is heated by a flame, its raising and lowering of potential is audible and the stages when the current reverses'are clearly distinguished in the difference intone.

I have found that by filling the inside of the case with parafiin wax all exterior disturbing sound waves are cut out, but care must be taken to prevent the paraflin wax ,running in between the bobbins and the cell and poles. To avoid this'I fill in the wax in a pasty semi-liquid state. In addition the wax serves as insulation and makes the structure of the magnets more firm, thus reducing the spring and synchronizing with the cell.

The cell is adapted and intended not only for use between the poles of a magnetic circuit, the poles of which are constructed of laminated sheet iron, annealed soft iron or a bundle of soft iron wires, surrounded by a magnet wire and charged bya permanent field or electromagnets, but also for separate or multiple use as shown in Fig. 4 wherein 39 is a permanent magnet, 40 the bobbin with its magnet, an the pole, 42 and 4:3

. bodied in a telephone receiver.

the cell is not as sensitive as 111 Fig. 1 as the having a spring 45 adapted to hold the car pieces in position in the ears.

In Fig. 6 I have shown my invention cm- In this form wirin and drum space are too'sinall to get full e ciency.

In Fig. 7 I have extended the pole pieces and the cell practically the full length of the telephone receiver.

When one of the openings 32 is plugged, the cell may be used for open speech and tones. When both of the openings are open and connected with ear pieces, thecell may be used in connection with wireless and telephone receiving stations as a receiver. In submarine signaling the thickness of the diaphragms should be proportionate to the depth to which the instrument is to be sub merged. For the detection of sound and tone waves in the earth, volcanic disturbances, mine signaling, etc., the cell must be embeded in sand or earth or immersed in water in close contact with the earth. To detect the direction of the source of the sound waves, deaden one of the diaphragms and face indifferent directions until the best results are obtained. The applicant has also discovered that the transverse membranous walls of his metallic cell will vibr ate at a place between opposite magnetic poles in response to externally induced currents, even when there is no intimate metallic connection either to the cell or the magnet or magnets, the poles of which directly influence it. A make or break in a current from a battery, dynamo or other electrical source, through a loop of wire or an aerial conductor, removed from the instrument and not connected with it by metallic connections, can be recorded by the instrument when the latter is properly placed.

What I claim is 1. In a device of the character described,-

and said wall inclosing a chamber having a thinness, comparing with the thickness of each diaphragm approximately as 10 to 1.

3. In a device of the character described, a cell comprising two flexible diaphragms and a wall joining said diaphrzigms together so as to form a flat cylindrical chamber between them, two opposite ports being formed in said wall, in combination with magnets on each side of said cell and magnetic poles between said magnets, the thickness of said chamber being approximately equal to the distance between each diaphragm and the nearest pole.

4. In a device of the character described, a cell comprising two flexible diaphragms and a wall joining said diaphragms together so as to form a flat cylindrical chamber between -them, two opposite ports being formed in said wall, in combination with permanent magnets, pole pieces for said magnets and magnet coils disposed between the cell and said permanent magnets, the distance between said cell and each of said pole pieces being equal to the distance between said diaphragms.

5. In a device of the character described,

a cell comprising two flexible diaphragms and an annular wall joining said diaphragms together throughout their perimeter, thus forming a thin cylindrical chamber within the cell, two opposite ports being formed in said wall, in combination with permanent magnets, pole pieces composed of laminated sheet iron for said magnets and magnet coils disposed between the cell and said permanent magnets, said cell being situated between said pole pieces and means for adjusting said pole pieces relative to said cell, whereby the distance between the cell and one of said pole pieces may be made equal to the thickness of said chamber.

6. In a device of the character described, a cell comprising two flexible diaphragms and an annular wall joining said diaphragms together throughout their perimeter, leaving a narrow cylindrical space bewteen them, two opposite ports being formed in said wall, in combination with magnetic coils disposed on opposite sides of said cell and central cores forming opposite poles in said coils, means to center the cell between said coils, whereby the distance between each pole and the cell will be made approximately equal to the thickness of said space.

7. In a device of the character described,

a cell having two flexible diaphragms with aunarrow space between them, in combination with pole pieces situated on two opposite sides of said cell and externally thereto, magnets grouped around said pole pieces,

8. An instrument for reproducing and. magnifying sound waves, comprising a cell having two flat, circular diaphragms fastened together around the periphery so as to form a sealed cylindrical chamber for a fluid, the thickness of said chamber comparing with its diameter approximately as 1 to 64; a member having connection with said chamber for receiving fluid therefrom and transmitting its fluctuations.

9.. An instrument for reproducing and magnifying sound waves, comprising a cell having two flat, circular diaphragms fastened together around the periphery so as to form a sealed cylindrical chamber for a fluid, the thickness of said chamber comparing with its diameter approximately as 1 to (i-l; a member having connection with said chamber for receiving fluid therefrom and transmitting its fluctuations, electromagnets on both sides of said cell provided with a central pole on each side of the cell and a sound proof non-magnetic casing for said cell, magnets and poles.

The foregoing specification signed at Baguio, Mountain Province, P. I., this 23rd day of May, 1913.

CLINTON HORACE HULBERT.

In presence of two witnesses:

JULIO ALUEZAN, ROBERTO Lnsmn'ro, 

